Did Deepwater Methane Hydrates Cause the BP Gulf Explosion?
According to the National Academy of Sciences, which published a bullish report on the energy potential of methane hydrates,
"Industry practice is to avoid methane-bearing areas during drilling for conventional oil and gas resources for safety reasons."
Professor Sum explained that because "with oil there is usually gas present," it is possible for methane hydrates to form in the pipe even when not drilling through hydrate-bearing sediments. The pressure and cold of the deepwater create conditions that encourage gas flowing into the pipe to form hydrates, and if the rate of crystallization is rapid enough, the hydrates can clog the pipe.
The cofferdam that BP lowered over the broken pipe gushing oil to contain the spill was almost immediately clogged by methane hydrates, which formed spontaneously. Gas escaping with the oil from the well, when trapped in the steel structure with cold water under great pressure, rapidly accumulated into an ice-like matrix.
Documented Explosive Hazard
In a book about methane hydrates, which Professor Koh co-authored, brief mention is made of a case in which methane hydrates caused a gas pipe to rupture on land, leading to loss of life.
Two workers were attempting to clear a line in which a hydrate plug had formed. The authors say that "the impact of a moving hydrate mass" caused the pipe to fail. The explosion caused a large piece of pipe to strike the foreman, killing him. The book then quotes from the Canadian Association of Petroleum Producers Hydrate Guidelines to describe proper procedures for safely removing a hydrate plug in a pipe on land.
SolveClimate was not able to find more detailed public documentation of this incident in Alberta, but mention is made in an article in a publication of the Oak Ridge National Laboratory, a federal research center associated with the Department of Energy, of a different unspecified incident on a drilling rig.
"Forces from methane hydrate dissociation have been blamed for a damaging shift in a drilling rig's foundation, causing a loss of $100 million," the article reports.
Although public discussion of damage from methane hydrate accidents appears to be minimal, the danger is well-recognized within the industry. Last November, one Halliburton executive gave a presentation before a meeting of the American Association of Drilling Engineers in Houston, titled "Deepwater Cementing Consideration to Prevent Hydrate Destabilization."
It recognizes that the cementing process releases heat which can destabilize methane hydrates, and presents something called Cement System 2 as a solution to the problem. One of the graphs shows that the system doesn't achieve gel strength for four hours.
Yet according to an eyewitness report broadcast on Sunday on 60 Minutes, BP managers made the decision to decrease pressure in the well column by removing drilling mud before the cement had solidified in three plugs Halliburton had poured.
When a surge of gas started shooting up the well, a crucial seal on the blowout preventer at the well head on the ocean floor failed. It had been damaged weeks before and neglected as inconsequential by Transocean managers, according to the CBS news broadcast, even after chunks of rubber emerged from the drilling column on the surface.
According to the Associated Press, the victims of the Deepwater Horizon explosion said the blast occurred right after workers "introduced heat to set the cement seal around the wellhead." It is not known if Halliburton was employing Cement System 2, and testifying before the Senate last week, a Halliburton executive made no mention of methane hydrate hazards associated with cementing in deepwater.
A Promising Substance
Professors Koh and Sum are concerned that a focus on the dangers of methane hydrates in deepwater drilling will obscure their promise as an energy solution of the future. They are conducting research in the laboratory to create methane hydrates synthetically in order to take advantage of their peculiar properties. With their potential to store gas (both natural gas and hydrogen) efficiently within a crystalline structure, hydrogen hydrates could one day offer a potential solution for making fuel cells operate economically. Still at the fundamental stage, their work on storage is not yet complete enough to apply to commercial systems.
At the same time, there is an international competition underway to develop technology to harvest the vast deposits of methane hydrates in the world's oceans. Japan has joined the US and Canada in pursuit of this energy bonanza, motivated by the $23 billion it spends annually to import liquefied natural gas.
According to a Bloomberg News article called "Japan Mines Flammable Ice, Flirts with Environmental Disaster," the Japanese trade ministry is targeting 2016 to start commercial production, even as a Tokyo University scientist warned against causing a massive undersea landslide that could suddenly trigger a massive methane hydrate release.
The U.S. has a research program underway in collaboration with the oil industry, authorized by the Methane Hydrate Research and Development Act of 1999. The National Methane Hydrates R&D Program is housed at the National Energy Technology Laboratory (NETL) of the Department of Energy.
The National Academy of Sciences provided a briefing for Congress last January on the energy potential of methane hydrates based on its report which asserts that "no technical challenges have been identified as insurmountable" in the pursuit of commercial production of methane hydrates. More...
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